/*
 * Copyright � 2002-2011 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

namespace Spring.Objects.Factory.Config;

/// <summary>
/// Implementation of <see cref="IVariableSource"/> that
/// resolves variable name against environment variables.
/// </summary>
/// <author>Aleksandar Seovic</author>
[Serializable]
public class EnvironmentVariableSource : IVariableSource
{
    /// <summary>
    /// Before requesting a variable resolution, a client should
    /// ask, whether the source can resolve a particular variable name.
    /// </summary>
    /// <param name="name">the name of the variable to resolve</param>
    /// <returns><c>true</c> if the variable can be resolved, <c>false</c> otherwise</returns>
    public bool CanResolveVariable(string name)
    {
        return (Environment.GetEnvironmentVariable(name) != null);
    }

    /// <summary>
    /// Resolves variable value for the specified variable name.
    /// </summary>
    /// <param name="name">
    /// The name of the variable to resolve.
    /// </param>
    /// <returns>
    /// The variable value if able to resolve, <c>null</c> otherwise.
    /// </returns>
    public string ResolveVariable(string name)
    {
        return Environment.GetEnvironmentVariable(name);
    }
}
